New one arrived today.

[fiver]

yep and you can tell if you got it too tight or too loose because the plate will tilt towards the bolt or away from it.
high cuts or fins close to the bolt too loose, away from it too tight.
another way to tell if you need more venting is to fill the mold real slow letting the air escape from the fill hole if it suddenly starts giving good bases you need to work the venting over.

I actually use a whet stone at a 45 to the square face and go all the way down the mold across the cavity's.

anyway I have had some slightly bent sprue plates, and a couple of concave ones that absolutely gave me fit's until I seen the problem and got after repairing it. [or replacing it]
one time I beat the living piss out of the plate with a 6 lb hammer until it was flat then I beveled the edges on the grinder.
not a recommended procedure, but I have fixed more than one mold with a hammer, they was headed to the trash anyway so that was the last stop.

 

[Ben]

they was headed to the trash anyway so that was the last stop.

When you reach that point, you don't have too much to loose.

Ben

 

[fiver]

yeah,,, dropping a Franklin into the trash really goes against my nature, but there really was nuthin left to lose.
plus I knew if it didn't work I'd at least feel better about it going in.

 

[StrawHat]

I also break the edge with a whet stone. For me, easier to get a consistent angle across the cavities as opposed to a file. All roads lead to Rome sort of thing.

Kevin

 

[Bisley]

I was going to ask, Ben, what are the dimensions on the file?

 

[USSR]

Okay, here are the results of today's casting session. Cleaned the mold one more time, even though I knew that wasn't the problem. Preheated the mold and loosened the sprue plate bolt so that the sprue plate was loosey goosey. I then opened the sprue plate up and stuck the tip of it into the molten lead for a minute. After doing all this, fill out was much better. I then increased the temperature of my Lyman Mag 25 to 760 degrees. I've never had to cast at this high of a temperature before, but this, in addition to the other things I did was the key. Having nearly a dozen of these molds, I've come to realize that my molds are like children, each one is a little bit different. However, this mold is definitely my little red headed step-child.

Don

 

[Ben]

I was going to ask, Ben, what are the dimensions on the file?

 

[USSR]

One other thing. fiver's post about "slightly bent sprue plates" has got me wondering. When I just slightly tighten the sprue plate bolt, the good base fill out on the 2 cavities near the bolt immediately goes away, while the other 2 cavities maintain their good fill out.

Don

 

[Ian]

This is a MP mould, right? Just a roll pin for a stop and no bolt head or flanged bushing to tuck the loose end of the sprue plate under? Getting the MP plates adjusted for a good balance of tension is a little tricky, generally they're set dead-on when they arrive though. Break the blocks (I use a 1" fine bastard file myself, but have a lot of practice with files) and adjust the pivot bolt so the sprue plate lies flat with just a little friction (not floppy loose, but almost so) and that should solve your problems. Filling the cavities too slowly will also cause rounded bases, as will too cool of a sprue plat (not enough extra metal run over the top. I like to pile the sprue into a huge thing covering most of the plate.

 

[fiver]

they do have personalities sometimes.

I like to set the plate by holding it up level with a light behind the mold and look between the mold and the plate.
you can see high and low spots easily that way.
and you can see the thin level line of light between them as you work the bolt once I get that that is where I set things and start from.
if I see something wavy or whatever I know where to look at the plate for further action.